In the production of various articles by machining methods, it is common to mount the part on an index table which moves the part through various successive stations at which various operations are performed. It is desirable that the positioning at each station be accurate in order that the parts are accurately formed and maintain dimensional tolerances.
In U.S. Pat. No. 4,049,252 issued Sept. 20, 1977, there is disclosed an index table which comprises a base, a table mounted about an axis for rotation of the base and means for indexing said table to bring successive stations of the table into predetermined positions. Spaced locating plates are fixed on said table at circumferentially spaced points, and radially movable locking pins are provided on the base and are movable by a cam radially inwardly to engage the locating plates and lock the table relative to said base, and are movable radially outwardly to disengage the table from the base. Upon rotation of the table to move the radial locking pins radially outwardly, a pump is operated to pump oil to various portions of the table.
Among the objectives of the present invention are to provided an improved index table wherein the table is locked accurately independently of any external radial pressure, wherein the index table can carry large loads having a high inertia factor, wherein the design can be readily adapted to different numbers of stations, wherein the index table includes an improved lubrication system, wherein the index table includes visual means for verifying that the table is properly locked in position, and wherein the table is provided with sensing means for producing an electrical signal which can be connected to electronics associated with the operation of the index table and the functions that are being performed.
In accordance with the invention, the index table comprises a base, a main plate mounted on the base, a drive wheel mounted for rotation on one side of the main plate about a first axis transverse to the main plate, a work plate on the other side of the main plate rotatably mounted about a second transverse axis spaced from the first transverse axis, and a segment wheel mounted on the one side of said main plate and fixed with relation to the work plate. Circumferentially spaced segment drivers are mounted on the drive wheel and are adapted to engage circumferentially spaced slots on the segment wheel to intermittently drive the segment wheel and in turn the work plate. A yoke plate is mounted on the one side of the main plate for movement radially with respect to the drive wheel and the segment wheel. As the drive wheel rotates, each segment driver engages the yoke plate and moves the yoke plate relative to the segment wheel. As the yoke plate is moved radially outwardly and inwardly, it swings arms pivoted to the main plate, moving pins on the arms into and out of engagement with the sides of a pair of adjacent spaced slots on the segment wheel to unlock and lock the work plate in position. Movement of the yoke plate also functions to operate oil pistons that supply lubrication to the index table.